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How to plot an exact sin wave in GUI when signal is acquired through function generator?

Vikas Bhardwaj89
Prodigy 40 points

Other Parts Discussed in Thread: CONTROLSUITE

I am using F28069 Control Stick in which i am trying to catch the sin wave from the funtion generator. I am running ContinuousADC program to acquire the analog signal that is coming from the function generator. There are 3 things that i want to ask. 

1) When i am giving the input with the signal generator through the probe it is not acquiring the signal. I am giving input to the pin2 and grounding with pin 32. But when i give the input without probe directly toughing the jumper wires with channel it is showing variation. Why? 

Is this  is happening because the probe is not compatible with the piccolo and piccolo is not able to detect the signal.?

2) Major problem.. Even when is am toughing the jumper wire with the input and it is changing it is not able to detect the signal with high frequency I am not able to configure why this happening. It is able to project 2-3 values/ second. I am totally new with the micro-controller from last 2 months i am trying to catch this signal but for no avail.  

3) There is CLA circuit also present in this micro-controller should i use that to plot the graph with more accuracy in the GUI. BUt there is a problem i donot knw how to use that neither the programming. :(

  • 0
    Guru 192875 points
    Hi Vikas,

    Are you using this example code: C:\ti\controlSUITE\device_support\f2806x\v151\F2806x_examples_ccsv5\adc_soc
    If not then try this! In this the ADCs INA4 and INA2 are configured.
    Secondly, probe attenuating the ADC Input is worrisome. Anyways, we'll come to this issue later. First lets get the input read correctly.

    Regards,
    Gautam
  • 0 in reply to Gautam Iyer
    Prodigy 40 points
    Hi Gautam Iyer,

    Thank you for your reply.

    As you told now i have used C:\ti\controlSUITE\device_support\f2806x\v151\F2806x_examples_ccsv5\adc_soc,

    the i made the video of acquiring the signal.

    https://youtu.be/prNX2PTUzqQ

    But i am not able to plot these things as the registers are not showing in the Volatge1 and Voltage2. As i have mentioned in the previous post i was able to see the changes in the register when i was using
    C:\ti\controlSUITE\development_kits\F28069 controlSTICK\ADC - ContinuousADC
    above programme and also to plot the reading by the register AdcResult.ADCRESULT2 but i was not able to make a perfect sine wave.


    Regards
  • 0 in reply to Vikas Bhardwaj89
    Guru 192875 points
    I can see variations in Voltage 2. You can't plot the on graph as the refresh rate of CCS Graph utility is 500ms to 1s. So unless your sine update rate equals 1sec or half a sec, you won't be able to see sine wave on the graph.

    Regards,
    Gautam
  • 0 in reply to Gautam Iyer
    Prodigy 40 points
    Hi Gautam Iyer,

    By this should i conclude that in GUI graph we can not plot exact sin wave when we are acquiring the analog signal from function generator. Thank you ..
  • 0 in reply to Vikas Bhardwaj89
    TI__Guru 60865 points

    Hi Vikas,

    If you want to produce a graph of your sine wave, you can capture the full waveform in a buffer in memory, then use tools->graph in CCS to plot the waveform. 

    If you want to plot it in real time, you could maybe stream the data out using the SCI peripheral over the emulator connection and then write a java/perl/python program to read the serial port and plot the data.  I think this will have a bit rate lower than the amount of data the ADC can generate, so if you want to plot high speed signals in real time, you may need to get some type of digital capture card for the PC and then stream the data in parallel over a group of F2806x GPIOs. 

  • 0 in reply to Vikas Bhardwaj89
    Guru 192875 points
    Yes, if you wish to get it LIVE then not possible but with some delay is possible refer to Devin's post.

    Regards,
    Gautam